Default Character Motor randomly jumping?

Hi, and sorry for providing such a non-specific question. I usually don't do this... Anyway, I am currently making a first person shooter game. I did NOT use the default First Person Controller, instead adding the 'CharacterMotor', 'FPSInputController', and 'CharacterController' components onto my player. When I walk around but more frequently shooting or sprinting, my character would launch himself into the air with a very high velocity. No, neither my muzzleflash nor my bullet has colliders on it(bullet = raycast). This also occurs 50% of the time when I pick up a gun, but my character throws the previous gun 1 meters away from him, so I don't see how the previous gun's collider can affect the character. Also, I remove the collider from the newly picked-up weapon, so that cannot affect the player either. Any help is appreciated.

Thanks in advance, william9518